dc.contributor.author |
Mittelstaedt, Eric |
dc.contributor.author |
Davaille, Anne |
dc.contributor.author |
Keken, Peter Edwin van |
dc.contributor.author |
Grácias, Nuno Ricardo Estrela |
dc.contributor.author |
Escartín, Javier |
dc.date |
2013-10-30T09:07:34Z |
dc.date |
2013-10-30T09:07:34Z |
dc.date |
2010 |
dc.identifier.citation |
1525-2027 |
dc.identifier.citation |
015023 |
dc.identifier.uri |
http://hdl.handle.net/10256/8529 |
dc.format |
application/pdf |
dc.language.iso |
eng |
dc.publisher |
American Geophysical Union |
dc.relation |
http://dx.doi.org/10.1029/2010GC003227 |
dc.relation |
Reproducció digital del document publicat a: http://dx.doi.org/10.1029/2010GC003227 |
dc.relation |
© Geochemistry, Geophysics, Geosystems, 2010, vol. 11, núm. 10, p.Q10005 |
dc.relation |
Articles publicats (D-EEEiA) |
dc.rights |
Tots els drets reservats |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Imatges -- Processament |
dc.subject |
Image processing |
dc.subject |
Fons marins |
dc.subject |
Ocean bottom |
dc.title |
A noninvasive method for measuring the velocity of diffuse hydrothermal flow by tracking moving refractive index anomalies |
dc.type |
info:eu-repo/semantics/article |
dc.type |
info:eu-repo/semantics/publishedVersion |
dc.description.abstract |
Diffuse flow velocimetry (DFV) is introduced as a new, noninvasive, optical technique for measuring the velocity of diffuse hydrothermal flow. The technique uses images of a motionless, random medium (e.g.,rocks) obtained through the lens of a moving refraction index anomaly (e.g., a hot upwelling). The method works in two stages. First, the changes in apparent background deformation are calculated using particle image velocimetry (PIV). The deformation vectors are determined by a cross correlation of pixel intensities across consecutive images. Second, the 2-D velocity field is calculated by cross correlating the deformation vectors between consecutive PIV calculations. The accuracy of the method is tested with laboratory and numerical experiments of a laminar, axisymmetric plume in fluids with both constant and temperaturedependent viscosity. Results show that average RMS errors are ∼5%–7% and are most accurate in regions of pervasive apparent background deformation which is commonly encountered in regions of diffuse hydrothermal flow. The method is applied to a 25 s video sequence of diffuse flow from a small fracture captured during the Bathyluck’09 cruise to the Lucky Strike hydrothermal field (September 2009). The velocities of the ∼10°C–15°C effluent reach ∼5.5 cm/s, in strong agreement with previous measurements of diffuse flow. DFV is found to be most accurate for approximately 2‐D flows where background objects have a small spatial scale, such as sand or gravel |